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WEEK 11 STUDY QUIZ - (DR) TFT Image Formation & CCD/CMOS already passed
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WEEK 11 STUDY QUIZ - (DR) TFT ImageFormation & CCD/CMOS
A Gd2O2S scintillator is known as what type of phosphor? - correct answer ✔✔Both A and B
When an image is digitized, - correct answer ✔✔each pixel has a brightness level representing the
attenuation characteristics of the volume of tissue imaged.
Digital radiography can be referred to as - correct answer ✔✔all of the above
Scintillators are phosphors that - correct answer ✔✔produce light when absorbing x-rays.
CCD chips are usually not larger than 5 x 5 cm; most range from - correct answer ✔✔2 - 4 cm.
What type of digital radiography device is composed of a photosensitive receptor and electronics
embedded in a substrate material in a silicon chip? - correct answer ✔✔CCD
Which type of phosphor is most common with CCD? - correct answer ✔✔Structured
All of the following are considered impurities except - correct answer ✔✔tellurium.
What is the function of the small capacitors used in CCDs? - correct answer ✔✔Converts light photons
into an electrical charge.
A device that temporarily stores charge is the - correct answer ✔✔capacitor.
Amorphous selenium (a-Se) has a - correct answer ✔✔low atomic number.
, _______ turn semi-conductors into full electrical conductors. - correct answer ✔✔Dopants
The pixel detector on the DEL is the area that - correct answer ✔✔absorbs x-ray photons.
To collect charge on silicon chips the voltage sign is changed on electrodes within each del moving
electrons by rows down columns until readout row is reached. This is referred to as: - correct answer
✔✔Bucket brigade scheme
Which of the following is not considered a scintillator? - correct answer ✔✔a-Se
Why is the thickness of amorphous selenium is high? - correct answer ✔✔To compensate for its low
atomic #.
Which of the following statements is true? - correct answer ✔✔Quantum efficiency will affect detective
quantum efficiency.
If offset correction is preformed before the previous image signal is cleared from the pixels, that residual
signal will be stored as inherent and could cause a ___________ of the residual signal. - correct answer
✔✔negative image
The bottom layer of a flat-panel detector is the - correct answer ✔✔glass base layer.
The most common types of noise that affects image quality include all of the following except - correct
answer ✔✔quantum noise.
All of the following statements are true except: - correct answer ✔✔Dead pixels at the edge of the
detector are easily identified.
The image information provided by the exit radiation is absorbed and converted directly into an
electrical signal containing the same image information. - correct answer ✔✔True
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